Sound level control system



De c. 2, 1941. M, ST 2,265,097

SOUND LEVEL CONTROL SYSTEM Filed, Jan. 31, 1959 I-u mum s u n d an o al 65241.0 M. Bets-7',

Patented Dec. 2, 1941 SOUND LEVEL CONTROL SYSTEM Gerald M. Best, Beverly Hills, Calif., assignor to Warner Brothers Pictures, Inc.,-a corporation of Delaware Application January 31, 1939, Seria l No. 253,905

8 Claims.

This invention relates to motion picture sound recording apparatus and particularly to a sound rerecording system wherein a plurality of sound records are simultaneously reproduced and recorded into a single composite sound record.

The general type of rerecording system Wherein a group of sound reproducers are operated simultaneously and the outputs thereof fed through a mixing panel to a recorder is well known in the art. The present invention is an improvement of such rerecording systems in the manner of maintaining the input to the mixing panel at a constant average uniform level. In the recording of different concomitant sound sequences for the different picture sequences, usually dialogue, each sound sequence does not always have the same average level thereon. These differences in level may be the result of causes, such as different recording machines, since some sequences may be recorded simultaneously, different recording operators, etc.

For the rerecording operation, the different sound sequences are spliced together and serially reproduced through a single reproducing machine, the output of which is fed to the mixing panel. The result is an output in which the average sound level varies from sequence to sequence.

Although the mixing operator has control over the level in this particular channel, he is usually unable to give the necessary attention to it since he is striving to obtain certain dramatic effects by properly combining the outputs of the various reproducers into the final sound track as he views the picture which is being simultaneously projected. He must also attend to the introduction of the various back-ground effects at the proper points in the picture and must maintain the proper balance between the dialogue and various background effects. Thus, if the inputs to his mixing panel are varying from time to time without notice, his mixing operation suifers.

The present invention, therefore, is directed to an automatic volume control located between the output of a reproducer and the mixing panel. In

. general, it includes an attentuator pad operated by a relay under controlof a breaker box actuated by notches in the film which have been made near the various splices of the different sequences. The level of each sequence is noted on an index card and the relay control is set according to the levels indicated on this card.

An object of the invention, therefore, is to control the amplitude levels of reproduced sound from a sound record.

A further object of the invention is to automatically vary the amplitude level of various sound sequences between the output of a sound reproducer and a sound recorder in accordance with the predetermined average level of the respective sound sequences being reproduced.

Afurther object of theinvention is to maintain a uniform average level of soundoutput from a reproducer reproducing a record having a series of sound tracks of different average levels.

Although the novel features which are believed -to;be characteristic of this invention will be pointed out with particularity in the claims appending herewith, the invention itself, its objects and advantages, the mannerof its organization and the mode of its-operation, will be better understood by referring to the following description read in conjunction with the accompanying drawing forming a part thereof, in which:

Figure 1 is a diagrammatic circuit arrangement embodying the invention; and

Figure 2 is a detail view of a portion of a sound 7 film being rerecorded showing the film control tions of the final sound to be recorded. For instance, film 1, being supplied from a reel 8 and taken up by a'reel 9, may contain all dialogue, or a combination of dialogue and musical passages recorded during the shooting of the scenes. The film l0, supplied from a reel l I and taken up by a reel [2, may contain certain types of background effects, such-as crowd noises and the like, while film l5, supplied by a reel l6 and taken up by a reel I1, may contain other types of background sounds, such as airplane .noises, hoofbeats, etc.

The film I is reproduced through the usual type of reproducing optical system comprising a lamp 2.0, lens 2| and photoelectriccell 22. Similarly, the film 1.0 is reproduced through opticalsystem .23, 1 4 and25; and film l5, through .a similar optical system :26, 27 and 28. The outputs of cells '22, 25 and 28 are all fed to a mixing panel 30, over conductors 3|, 3'2 and33, respectively. On the mixing panel '30 is shown a plurality of control knobs 35 whichactuate impedances known as mixing pots for varying the amplitude of the currents from the cells 22, 25 and 28, the

7 balance thereof being observed'by the mixing operator in the monitor loudspeaker 36 connected over conductors '31.

As far as has been described, this is the general type of rerecording system whereby the output of the mixer 30 is fed over conductors 38 into a recorder 39 for making a master negative 40, supplied from a reel 4| and taken up by a reel 42.

As mentioned above, in the making of sound negatives, the recording usually occurs at different times and under different conditions so that although an attempt is made to maintain a certain uniform recording level, it frequently happens that the average levels for the various sound sequences vary to a considerable degree. That is, one scene may be at 50% modulation, another at 60%, and anotherat 35%, etc. If these various levels were reproduced in the theatre, it would not only be annoying to the listeners, but certain sequences might even be eliminated by the background effects. It is realized, of course, that the mixer at panel 39 could control these levels to a certain extent, but

this is diificult, as explained above. j

, The present invention, therefore, is adapted to automatically equalize the various sound levels from the film 1 before they reach the mixing panel 30.

This is accomplished by providing a series resistance 41 and a shunt resistance 48, the

' amount of each inserted in the circuit between comprises a magnetic solenoid which, when energized, releases the rod 52 and allows it to take a position previously set by lever 55. A plurality of holes 56 is provided for setting the lever 55 in different positions in accordance with a previously prepared index card. As shown, there are ten holes provided, each of which varies the attenuation pad 41-48 two db. Thus, should the handle 55 be set at a certain position difi'erent fromthe one previously set, then upon energization of the solenoid, the mechanism will adjust itself to the pre-set position. Thus, after each trip, the lever is set to the next position, as shown on the index card which indicates the setting of the lever in the holes 55.

The solenoid within the control box 54 is operatedrby. a breaker switch box 51 over conductors 58, this breaker switch being shown in Fig. 2 as a roller 6|] mounted on an arm BI and bearing against the edge of the film 64 under tension of a spring 62, contact being made or broken at point 53. The positive film 64 is notched as shown at 55 according to the position of thesplices of the various sequences. As

shown, a strip 61 is shown spliced to a strip 68, the strip 61 being shown with a higher level sound than the strip 68. In this case, the notch 65 is placed in a position so that it will energize the solenoid within the control box 54 and thus set the attenuator to a position set by the arm 55. Thus, the entire negative film will be prepared with notches to actuate the attenuator 41- 68 in accordance with the levels of the The index card is, of course,

cessive sequences. This card is given to the rerecorder operator, who will set the lever 55 aftereach energization, according to the indications on thecard. Thus, in operating the present system, the dialogue or other sounds upon the film .1 will arrive at the mixer panel 30 at an average uniform'level 'so'that the fmixer may devote his entire time to obtaining the proper dramatic effect of the combined sounds.

It is to be understood that the above-described equalization may also be applied to additional channels, such as 32 and 33. Also, other types of control units, such as disclosed in U. S. Patent 1,474,409 of November 20, 1923, to O. B. Depue, may be used for control unit 54, such units using a plug board which may be pre-set for a plurality of consecutive sequences. With such a unit, a full film reel could be reproduced without manual attention depending on the number ofchanges required and the capacity of the unit.

I claim:

1. A sound recording system comprising a sound film reproducer adapted to reproduce a sound film consisting of a series of sound sequences of different average sound levels, a sound recorder, means interconnecting said reproducer and recorder, means included in said last-mentioned means adapted to be pre-set in accordance with the difference between the average sound levels of said sequences for varying thetransmission between said reproducer and recorder, and means actuated by said film in said reproducer for controlling said transmission varying means.

2. A. sound recording system in accordance with claim 1 in which said transmission varying means comprises a variable impedance network and means for varying the effective amount of said impedance in said network, variations in the film of said reproducer being adapted to vary said effective amount of impedance in accordance with the predetermined variations be tween said average sound levels.

3. A sound recording system comprising a plurality of sound reproducers, at least one of -which reproduces sound sequences at varying ducers, and means in the interconnecting circuit for'said reproducer reproducing sound at varying average levels, said means being adapted to be manually pre-set in accordance with the variations in the average levels between said sound sequences, said means being actuated by modifications to the film having sound sequences of varying average levels.

4. A sound recording system comprising a plurality of sound reproducers, at least one of which reproduces sound sequences at varying average levels, ,a sound recorder, circuits interconnecting saidreproducers and said recorder for recording the outputs of all of said reproducers, and means in the interconnecting circuit from said reproducer reproducing sound at varying average levels for maintaining said levels substantially uniform, said last-mentioned means including a variable impedance and means for pre-setting said impedance in accordance with the predetermined variation between said average sound levels.

5. A sound rerecording system comprising a sound film consisting of a plurality of serially connected sound film sequences in which the average sound level varies between succeeding sequences, means for translating said sound sequences into corresponding electrical currents, a sound, recorder, means for connecting said translating means with said sound recorder, an

attenuator in said connecting means, and independent'means interconnecting said film and average sound levels of -successive sound sequences of said sound film, said last-mentioned means being adapted to be manually pre-set in accordance with the difference between the average sound levels of successive sound sequences of said sound film.

6. A sound rerecording system comprising a sound film consisting of a plurality of serially connected sound film sequences in which the average sound level varies between succeeding sequences, means for translating said sound sequences into corresponding electrical currents, a sound recorder, means for connecting said translating means with said sound recorder, an attenuator in said connecting means, means for varying said attenuator in accordance with the difierence between the average sound levels of successive sound sequences of said sound film, and means for actuating said attenuator varying means, said actuating means being under control of said sound film.

'7. A sound rerecording system comprising a plurality of sound films, at least one of said films consisting of a series of sound sequences of different average sound levels, means individual to each of said sound films for producing electrical currents corresponding to the sound thereon, a sound recorder for simultaneously recording all of said currents, a mixing panel connected intermediate said current producing means and said sound recorder, a variable attenuator connected between said current producing means for said film of different levels and said mixing panel, and means operated by said film of diiierent levels for varying said attenuator in accordance with the average volume level of each sequence of said film.

8. A sound rerecording system in accordance with claim 7 in which said last-mentioned means comprises an electrical circuit breaker operated by notches in said film and an electrical solenoid controlled thereby.

GERALD M. BEST. 

